This invention relates generally to sputter etch and deposition systems, and, more particularly to an etch and deposition apparatus which incorporates therein a centrally located anode in order to assist in the sputtering operation when utilized with concave surfaces.
In recent years the demand in the electronics industry, for example, for films with qualities difficult or even impossible to attain by deposition techniques already available, has led to the utilization of sputtering as a method of depositing a thin film coating on a surface. In addition, the sputtering technique has been utilized for the cleaning and etching of surface contaminants or other layers of material which are not desired from the surface of an article.
Unfortunately, a basic problem still exists in the sputter cleaning of the inside of a small hemispherical cavity. The standard technique for sputter cleaning was simply to apply a negative bias to the article to be cleaned in a glow discharge or plasma. It was then discovered that because of the shape of the cavity and its small size that the effectiveness of the sputtering technique decreased greatly when the effective diameter of the concave surface of the cavity is of the order of the Crookes dark space or smaller. For example, such sputter cleaning techniques of the past were relatively ineffective in cleaning the interior of a hemispherical cavity of 3/8 inches in diameter. Consequently, it can be seen that past sputter cleaning techniques utilized with articles having concave surfaces require substantial improvement to be effective.